Hemodynamic and renal functional studies will be conducted in isolated blood perfused canine kidneys. The role of nonabsorbable anions will be studied as an obligate to urinary acidification in the isolated kidney. The synthesis, metabolism, and excretion of catecholamines will be evaluated in this preparation. Vascular reactivity and tachyphylaxis to vasoconstrictor hormones will be assessed relative to prostaglandin formation and polypeptide hydrolysis.